1. Field of the Invention
The present invention relates to a roll arrangement for the non-deforming treatment of moving web-type or strip-type products. The arrangement includes at least two rotatable rolls which are adjustable radially and axially relative to each other. The arrangement is used, for example, for drying one or both surfaces of the product.
2. Description of the Prior Art
The term "non-deforming treatment" mentioned above refers to a procedure in which two rolls act on a moving web-type product under such low pressure that essentially no permanent change of the contour or shape of the product takes place. However, this requirement does not exclude a change of the surface of the product, nor does it exclude a reduction in thickness of the product caused by dewatering, as it occurs in the production of paper by dewatering a fiber mat as an intermediate product. In that situation, a reduction in thickness is a secondary effect of the primarily desired dewatering of the intermediate product by means of pressing rolls.
The invention is based on the expedients that frequently moisture residues remain on a web or strip when the surfaces of solid web-type or strip-type products such as, for example, steel strip, are dried by means of pressing rolls in rolling mills or web treatment units. This is apparently due to the fact that the pressing action of the rolls is not uniform over the width of the products. This non-uniform pressing action is due to two reasons; the rolls bend under their own weight or due to the pressing forces acting on the roll journals, or the web or strip itself does not have a uniform thickness, i.e., it does not have plane-parallel surfaces. Of course, bending of the pressing rolls can be compensated by cambering the roll bodies or barrels by supporting the rolls by means of support rollers or support rolls. However, these measures do not permit quick adjustments to compensate for changing deviations from the contour of the web or strip or for changes in the forces acting on the web or strip.
To be able to quickly adjust a roll body into a shape deviating from the cylindrical, the so-called bending-controlled roll was developed in the paper industry for pressing rolls. Such a bending-controlled roll includes a fixed shaft, a rotatable cylindrical wall and a number of hydraulic pressure devices with pressure shoes supported by the shaft, the pressure devices being arranged distributed over the length of the roll and acting on the inner surface of the cylindrical wall, so that this wall can be shaped into any desired contour. However, such bending-controlled rolls are structurally very complicated and are only economical when the web or strip to be treated is very wide, as is the case in paper production or in rolling plastics material sheets, as disclosed in German Patent 2,165,118.
It is the primary object of the present invention to provide a roll arrangement for the non-deforming treatment of moving web-type or strip-type products, with at least two rotatable rolls which are radially adjustable relative to each other, which arrangement makes it possible to compensate quickly and in a structurally simple manner the negative influences resulting from bending of the rolls and non-uniform shape of the products.